Controllers

An Ingress Controller is a component responsible for managing and fulfilling ingress rules defined in the Ingress resource. It acts as a reverse proxy and load balancer, enabling external access to services running within the Kubernetes cluster. The Ingress Controller listens to changes in the Ingress resources and configures the underlying load balancer or other networking components accordingly to route incoming traffic to the appropriate services.

Comparison Table #

Below is a comparison table for some popular Kubernetes ingress controllers:

Popular Ingress Controllers #

Nginx #

This is one of the most widely used Ingress Controllers. It uses the Nginx web server as a reverse proxy to manage the incoming traffic.

Nginx controller has different options that can be used to customise the way it works, like adding headers or rewrites. The options can be seen in the Nginx Ingress Controller Documentation

The Nginx Ingress Controller has its own Deployment and Service resources to manage the controller’s pods and expose them as a service in the cluster. To deploy nginx ingress controller, create a file named nginx-ingress-controller.yaml and add the following content:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  namespace: nginx-ingress
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx-ingress-controller
  template:
    metadata:
      labels:
        app: nginx-ingress-controller
    spec:
      containers:
        - name: nginx-ingress-controller
          image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:latest
          args:
            - /nginx-ingress-controller
            - --configmap=$(POD_NAMESPACE)/nginx-configuration
          env:
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
          ports:
            - name: http
              containerPort: 80
            - name: https
              containerPort: 443
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-ingress-controller
  namespace: nginx-ingress
spec:
  selector:
    app: nginx-ingress-controller
  ports:
    - name: http
      port: 80
      targetPort: http
    - name: https
      port: 443
      targetPort: https

Apply the configuration to your cluster:

kubectl apply -f nginx-ingress-controller.yaml

Traefik #

Another popular Ingress Controller that is known for its simplicity and ease of use. It also supports dynamic configuration and integrates well with various cloud providers.

To use Traefik as your ingress controller, you need to deploy it in your Kubernetes cluster and configure it to listen for ingress resources. Below, an example of how to deploy Traefik in Kubernetes is provided.

Create a file named traefik-ingress-controller.yaml and add the following content:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: traefik
spec:
  replicas: 1
  selector:
    matchLabels:
      app: traefik
  template:
    metadata:
      labels:
        app: traefik
    spec:
      containers:
      - name: traefik
        image: traefik:v2.5
        ports:
        - name: http
          containerPort: 80
        - name: https
          containerPort: 443
---
apiVersion: v1
kind: Service
metadata:
  name: traefik-service
spec:
  selector:
    app: traefik
  ports:
  - name: http
    port: 80
  - name: https
    port: 443

Apply the deployment using the following command:

kubectl apply -f traefik-ingress-controller.yaml

HAProxy Ingress #

HAProxy is a high-performance TCP/HTTP load balancer, and the HAProxy Ingress Controller leverages its capabilities to manage ingress traffic.

To deploy the HAProxy Ingress Controller in your Kubernetes cluster, you’ll need to create a deployment and a service. Below are the example YAML files for deploying HAProxy Ingress Controller.

Create a file named haproxy-ingress-controller.yaml and add the following content:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: haproxy-ingress-controller
spec:
  replicas: 1
  selector:
    matchLabels:
      app: haproxy-ingress-controller
  template:
    metadata:
      labels:
        app: haproxy-ingress-controller
    spec:
      containers:
      - name: haproxy-ingress-controller
        image: haproxytech/kubernetes-ingress
        args:
        - --default-backend-service=$(POD_NAMESPACE)/default-http-backend
        - --publish-service=$(POD_NAMESPACE)/haproxy-ingress-controller
---
apiVersion: v1
kind: Service
metadata:
  name: haproxy-ingress-controller
spec:
  selector:
    app: haproxy-ingress-controller
  ports:
  - name: http
    port: 80
    targetPort: 80
  - name: https
    port: 443
    targetPort: 443

Apply the deployment using the following command:

kubectl apply -f haproxy-ingress-controller.yaml

Contour #

Built on top of Envoy Proxy, Contour provides advanced features and is well-suited for large-scale and complex setups.

Istio #

Although primarily known as a service mesh, Istio can also function as an Ingress Controller, offering advanced traffic management features.

Each of these controllers has its own configuration and setup process. When setting up an Ingress Controller, you need to deploy the controller itself as a separate component within the cluster. The controller watches for changes in the Ingress resources and configures the necessary load balancing and routing rules accordingly. Depending on the Ingress Controller you choose, the setup and configuration may vary slightly.

It’s important to note that an Ingress Controller should be complemented by an Ingress Controller Provider to expose the controller to the external network. The Provider could be a cloud provider’s load balancer or an external service that manages the external traffic flow to the Ingress Controller.